Break the eggs into a bowl and whip up with a hand mixer until it becomes thick. Whip until you can draw lines with it.
Break the chocolate into pieces and put it into a heat proof bowl. Line the cake pan with parchment paper.
Add milk to the chocolate and heat up for 1 minute, while checking it, in a 500W microwave to melt. If you heat it up too much, it will get hard, so be careful.
Right after melting, stir with a whisk and make it smooth.
Add a little bit (about a ladleful) of step ① to the chocolate from step ④ and mix. When it is mixed smoothly, add step ① in two portions and mix.
Further mix with a hand mixer until the mixture becomes thick. Then pour the dough into the cake pan.
Bake in a 180℃ oven without preheating for 25 minutes. When the cake is ready, keep it in the oven for about 10 minutes in the residual heat.
It is ready. It sill shrink when it is cool but it will not be completely flat. If you like, sprinkle some powdered sugar on it using a tea strainer.
You can also bake it in a cupcake cup. Bake it in tall muffin cups and squeeze some whipped cream on top and have it for Valentine's Day.
If you are using muffin cups, it will be for 6 to 8 pieces. Pour the dough in the cups until about half to 80 percent high.
It doesn't shrink like when you bake it in a cake pan. I squeezed some cream inside and topped some on top.
Story Behind this Recipe
After making this recipe several times, I came up with this process that works well. I wanted to make the process easy and to have few dishes to wash, so I made this. Things to use are only 2 heatproof bowls, hand mixer (and whisk).
I whipped up the eggs without separating and made the process easier. Anyway, just whip it up until it is foamy and thick. If you whip it up thickly even after adding the chocolate, it will be more difficult for the cake to shrink even when it is cold. There are no flours or baking powder in it, so it won't raise so much. Therefore the point is to whip it up stiffly.